1. Field of the Invention
The present invention generally relates to a linear transmission mechanism, in particular, to a telescoping rod of a linear actuator.
2. Description of Prior Art
The linear transmission mechanism commonly seen in current market, for example, linear actuator, is a kind of assembly driven by motor, gear set, and connecting rod, etc., wherein a lead screw is brought along to rotate by the power generated from the motor, so that it may facilitate a telescoping rod generating an telescoping action in linear direction, by which other assembly connected to the telescoping rod may generate pushing and pulling actions, which are generally seen in our daily lives, for example, a patient bed moved vertically and a mini-elevator loaded with objects, which are all application examples of linear transmission mechanism.
In particular, the telescoping rod is one critical component to be connected to other assemblies, and the stability of the connecting structure of the telescoping rod will directly influence the pushing and pulling actions to be brought along and generated smoothly. As shown in FIG. 1, according to a prior structure, a universal joint 102 is screwed on top of a telescoping rod 101 and has an accommodating groove 103 penetrating the main body thereof for facilitating a connecting element to be accommodated in the accommodating groove 103, whereby a connecting relationship between the telescoping rod 101 and other assemblies may be secured. However, since of the high cost of the universal joint 102, its inventory cost is relatively high for manufacturers.
As shown in FIG. 2, according to another prior structure, an accommodating groove 103 is directly disposed at the rod head of a telescoping rod 101, and a sleeve 104 arranged in the accommodating groove 103a is tightly fitted and connected therein for facilitating a connecting element to be arranged in the sleeve 104. Although this structure may lower down the cost significantly, it is difficult to install other sleeve 104 with different outer radius in any time. Once a sleeve 104 is tightly fitted into the accommodating groove 103a, the linear transmission mechanism can only be matched with a connecting element with an outer radius same as the inner radius of the sleeve 104, thus causing an inconvenient usage. Furthermore, it is easy to make the sleeve 104 generate wearing deformation and dropped off after long usage, so there is a worrisome on structural security as well.
As shown in FIG. 3, a further prior structure is to arrange a radial accommodating groove 103a at the position of the rod head of a connecting rod, and a sleeve 105 is formed and secured in the accommodating groove 103a by means of powder-pressing process, whereby the drawback of easy wearing and deformation according to aforementioned structure that is constructed by tight fitness may be avoided. However, this kind of method still has the difficulty to install other connecting element with different radial size. Furthermore, since the sleeve 105 is made of powder material under a powder-pressing process of high temperature and high pressure, its structure is easily squeezed to incur smashing phenomenon, which is dangerous to the connected structure in terms of safety and stability.
Therefore, under the considerations of structural safety and the convenience of changing parts besides cost expense, it is indispensable to perceive a solution to overcome the drawbacks of prior arts.